In heavy components made in boiler factories, in particular pressurized water nuclear reactor vessels, pipe outlets or inlets in the tank or tappings are formed in the wall of the vessel so as to permit the connection, outside of this vessel, between the tapping and an inlet or outlet pipe.
Such tappings are formed in the wall so that the tapping is flush with the inner surface of the tank and projects fairly widely outside the tank to connect it with a pipe of the primary circuit of the reactor bringing water under pressure into the tank, or enabling the outflow of this water, which acts as coolant in the core of the reactor, from the vessel to the steam generators.
The inner surface of the vessel as well as of the tappings must be coated with a layer of stainless steel, and the quality of this coating must be checked, in particular within tappings formed in the wall of the tank.
Such checks assume a very good surface condition of the coating, and the entire inner surface of the tapping must be milled before commencing the checking operation.
On the other hand, when defects are detected, it is necessary to carry out machining in greater depth in order to determine the depth of these defects.
To carry out the machining operations or the checking operations, a tool or a checking means must be moved inside the tapping into different positions, enabling the various areas of the lateral surface of the tapping to be reached.
In the case of pressurized water reactor vessels, the borings or checks inside the tappings of the primary circuit are generally performed when the vessel is in vertical position, i.e., with tappings whose axes are practically horizontal.
To date, these operations are performed manually and are extremely arduous since it is necessary to work with very different positions of the tool although the internal diameter of the tapping is relatively small.
In the same way, the sound execution of the work inside the tapping is hampered by limited accessibility, the internal diameter of the tapping being relatively small. In certain cases, the space available is not even sufficient to permit the use of certain types of tools.
In addition, tappings of pressurized water inlet pipes in the vessel of the reactor have a conically shaped bore which further complicates manual machining for the purpose of achieving a good surface condition.
More generally, when it is desired to carry out machining or checking operations in tappings formed in the wall of a large sized boiler-made component, difficulties are encountered due to the exiguity of the space within which the machining is to be done, to the various positions that the tool or the checking means must be made to assume to follow the inner surface of the tapping, and to the fact that the inner bore of these tappings is not always cylindrical.
It is therefore an object of the invention to provide a device for supporting and moving a tool within a tapping having a symmetry of revolution and traversing a wall so as to be flush on one side of the wall and project on the other side, this device enabling automatisation of the work carried out with the tool, and accurate positioning of the tool with respect to the surface to be worked inside the tappings.
It is another object of the invention to provide a device for supporting and moving a tool within a tapping which device is adaptable to different types of profile and to different bore sizes.